Ink-jet recording apparatuses (hereinafter, also referred to as ink-jet printers) are usually low in noise, enable high-speed printing and facilitate multi-color recording by use of plural ink nozzles, so that they are broadly employed as an image information outputs unit of computers. Further, the use thereof has spread to color reproofs and designed images.
As an ink for use in ink-jet printers is generally employed a water-based ink mainly comprised of water and aqueous-soluble organic solvent to prevent ink clogging of nozzles and improve discharge property. As a recording sheet are employed conventional paper and a so-called ink-jet recording sheet comprising a support and provided thereon a porous ink absorbing layer. However, these recording sheets result in marked ink blurrings and low glossiness, which do not meet recent requirements for high image quality. In cases where a conventional porous ink absorption layer is provided on a film or glossy resin-coated paper, the porous ink absorption layer has a rough surface to produce irregular reflection, resulting in disadvantages such that transparency or glossiness is lost. In the case of a non-porous ink absorption layer, light transmission is improved but ink absorptivity deteriorates, producing problems such that after image printing, ink remains on the surface for a long time and the dry-fixing time becomes longer.
To solve the above problems, gelatin can be employed as an ink absorption layer exhibiting high light transmissivity and superior water-based ink absorptivity. There are proposed a absorption layer formed with an aqueous gelatin solution with a specified pH value, as described in JP-A 62-263084 (herein, the term, "JP-A" means an unexamined and published Japanese Patent Application), the use of a mixture of gelatin and surfactant, as described in JP-A 1-146784, and a recording sheet obtained by gelating coated gelatin and drying by a cold-drying method, as described in JP-A 6-64306. Although the ink receiving layer employing gelatin is superior in ink absorptivity and glossiness, it is inferior in ink fixability, having the disadvantage that dyes contained in the ink leach out when wetted with water.
There is reported a technique of using a water-soluble cationic polymer for the purpose of enhancing water resistance of prints, as described in JP-a 61-61887 and 61-63477. From the inventors' study, however, it was proved that even if this water-soluble polymer is applied to the gelatin ink absorption layer, sufficient water resistance can not be achieved and print quality is still deteriorated.